RF25 | PMON50 Insight into Integrated Control of Pituitary Function Revealed Through Analysis of Musashi Target mRNAs

Abstract The anterior pituitary controls growth, metabolism, reproduction and stress responses through the synthesis and secretion of specific hormones. Distinct cell lineages within the anterior pituitary generate specific hormones. Interestingly, the anterior pituitary exhibits a high level of adult cell plasticity that allows committed hormone-producing cells to alter their cell fate and produce different hormones to meet altered organismal demands. The molecular mechanisms underlying this adult cell plasticity have not been fully characterized. Our recent work has implicated the stem cell determinant and sequence-specific mRNA binding protein, Musashi, as a regulator of pituitary cell plasticity. The mechanisms by which Musashi controls pituitary cell plasticity are unknown. In this study, we have sought to identify the mRNA regulatory targets of Musashi in the adult mouse pituitary. Through the use of Musashi-RNA-immunoprecipitation we report a cohort of 1192 pituitary mRNAs that specifically interact with Musashi. mRNAs specific to each of the hormone-producing cell lineages were identified, as well as mRNAs specific to immature stem and progenitor cell lineages. The biological pathways encoded by the Musashi-enriched mRNAs include cell adhesion, cellular homeostasis, unfolded protein responses, protein trafficking, endocrine processes and female pregnancy. Functional analysis of validated mRNAs reveals both activating and inhibitory control of mRNA translation by Musashi. Together, our findings indicate a broad and complex role for Musashi in the post-transcriptional regulation of adult pituitary function. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m., Monday, June 13, 2022 12:58 p.m. - 1:03 p.m.